The present invention relates generally to erosion control and more particularly to devices and apparatuses for use in controlling pollution, silt, sedimentation and debris flow associated with soil erosion.
Controlling soil erosion, such as erosion on slopes in construction sites, and particularly the sedimentation and debris carried in fluid flow on slopes is a continuing problem. Fiber rolls (also known as wattles) are the current industry standard for use in controlling erosion. Fiber rolls are typically made of fibrous materials such as straw or excelsior (shredded wood) made into rolls that are held together with netting. During construction, the rolls are placed across the face of a slope to curtail soil erosion and to dam, direct and/or filter fluid flow as the fluid flows down the slope. Silt fences, generally black porous cloth strung vertically on wooden stakes across a slope, are alternative means of controlling erosion. However, most regulatory agencies now discourage the use of silt fences due to the propensity for silt fences to collapse from high fluid flows and high winds. Fiber rolls have been found to be more capable of performing the erosion control function than silt fences. However, fiber rolls are deficient in their ability to direct fluid flow in a controlled manner. Moreover, numerous fiber rolls are generally required due to their inherent deficiencies in directing fluid flow as the flow proceeds down a slope.
Furthermore, in response to tighter guidelines recently imposed by the federal Environmental Protection Agency under the Clean Water Act, controlling pollution and erosion from storm water runoff is receiving ever-increasing attention at all levels of government, federal, state and local. Federal and state agencies have issued mandates and developed guidelines regarding the prevention of non-point source (storm water caused) pollution that require local governments to act upon or initiate. These mandates also affect water runoff from storms and other sources on slopes and construction sites. Fiber rolls or xe2x80x9cwattlesxe2x80x9d have traditionally done a poor job of controlling or filtering pollution, debris or sediment from fluid flows, however, as water or runoff that flows from a fiber roll is typically substantially similar in nature to the water or runoff that flows into the fiber roll.
Chitosan is a well-known material that is derived from a naturally occurring substance called chitin, which is a polysaccharide found in the exoskeleton of shellfish such as shrimp, lobster, and/or crabs. While chitosan has recently gained popularity as a dietary supplement, its inherent ability to generate small electrical charges has also provided benefits in the processing of contaminated items, such as wastewater. In turbid or polluted water, the electrical charges given off by chitosan react with the small electrical charges in pollution, fine silt and sediment particles, such that many of these tiny bits of contamination and silt coagulate together into larger chunks. These larger coagulated chunks of particles can then be filtered more easily from the fluid and are also more prone to settle to the bottom of the fluid body via gravity. An appropriate application of chitosan can render a body of muddy water as fairly clear in a short period of time. While chitosan and chitin have been previously used to some extent in the treatment of wastewater, their use has yet to reach the field of storm water runoff with its accompanying objective to filter or clarify such water. Accordingly, more effective devices and systems are desired for controlling soil erosion and debris flow, and for filtering or clarifying fluid passing through such devices and systems.
The present invention comprises a walled elongated core member having a first open end, a second end, an interior space and one or more openings in the wall communicating the interior space with the exterior of the core member. An outer filter member surrounds the core member. In one embodiment, both the first and second ends of the core member are open. One feature of the present invention is the ability to connect a plurality of core members together. Accordingly, one or both of the open ends can comprise couplers or connectors for connecting one core member to one or two complimentary core members. The core member may comprise a flexible plastic pipe, such as high-density polyethylene pipe having a plurality of perforations.
In another embodiment, the couplers can comprise tee connectors or elbow connectors. One advantage of the present invention is the ability to connect outlet pipes to tee or elbow connectors for directing fluid flow received by the core members to desired locations downstream of the core members.
The outer filter member may comprise a fiber roll. In one embodiment the fiber roll comprises excelsior or straw. In another embodiment, the filter member may comprise a porous foam material. A porous covering material, such as a woven cloth or netting may surround the outer filter member.
In another embodiment, the elongated core member is corrugated, comprising a plurality of ribs extending along a least a portion of the exterior surface of the core member. One or more openings in the ribs communicate the interior of the core member with the exterior surface of the core member.
In another embodiment, the elongated core member comprises a flexible material have an interior space that is at least partially filled with a ballast material such as sand, gravel or the like. The elongated core member may further comprise openings communicating the exterior of the core member with the interior of the core member. One or more core members can be coupled together and strategically arranged to control the flow of sedimentation and debris.
In yet another embodiment, chitosan is applied to one or more parts of the fiber roll, preferably before the fiber roll is assembled. While a liquid form of chitosan is preferred, any other form, such as a powder, may be applied to the fiber roll. In the preferred embodiment, a liquid solution of chitosan is thoroughly sprayed onto a flat blanket comprising the outer filter member before this blanket is rolled around the elongated core member. This outer filter member preferably comprises excelsior, and is preferably left to dry for a period of time after the liquid solution is applied. Once assembled, the chitosan enhanced fiber roll is capable of coagulating fine solids in fluids, such that passage of pollution, silt and sediment through the fiber roll is reduced.